This invention relates to a process and an apparatus for opening the sealing or top flaps of a carton or cardboard box. More particularly, the invention relates to a process for spreading or for folding open the sealing flaps of cartons already sealed on the bottom side in order to allow packaging thereof.
Paperboard cartons having open top flaps and previously sealed bottom flaps are often used for packaging. If, for example, on a letter envelope packaging machine, the cardboard boxes or cartons are pushed over a stack of letter envelopes from above, it is necessary that the still-open sealing flaps, which are at the bottom during this packaging step, are in a position which does not interfere with the packaging operation. In particular, the flaps must not get in the way of the material being packaged. Consequently their adjacent free edges should be folded as far away from the box as possible, i.e., the edges should be pointing outwardly. To accomplish this result the prior art apparatuses use, for example, suction elements or swinging arms, by means of which the flaps are brought into the desired open position. The problem with the prior art equipment is that these known devices depend on the carton dimensions, i.e., they have to set up for whichever box sizes are being processed, and they have to be changed when the dimensions change. This requires a longer machine shutdown time to modify the machine to accept different boxes. Moreover, controlling and storing the suction elements and swinging arms is complicated and expensive and, therefore, susceptible to breakdown.